Powdered metal compacting press



July 23, 1963 J. J. LITTLEY ETAL POWDERED METAL COMPACTING PRESS FiledJan. 6, 1961 4 Sheets-Sheet 1 F16. Ia.

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July 23, 1963 J. J. LlTTLEY ETAL POWDERED METAL COMPACTING PRESS 4Sheets-Shet 2 Filed Jan. 6, 1961 u w 4 I 1 B 3 7 J M W M w 2% A 5 5 MM gy mum u 3 I m h I: L 9 N Q mm J z, J W fi Q 7 J Y 2 w ll 4 1 n r: w. 4FB J J a ATTORNEYS.

July 23, 1963 J. J. LlTTLEY ETAL POWDERED METAL COMPACTING PRESS 4Sheets-Sheet 3 Filed Jan. 6,v 1961 INVENTOR. JOHN J. LITTLEY AND, yROBERT Bums,

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ATTOR N E YS y 1963 J. J. LlTTLEY ETAL 3,

POWDERED METAL COMPACTING PRESS Filed Jan. 6, 1961 4 Sheets-Sheet 4 g YJ 1 1 JNVENTOR. JOHN J. LITTLEY AND y ROBERT BURNS,

ATTORNEYS.

United States Patent M 3,093,261 POWDERED METAL COMFACTLING PREES JohnJ. Littley and Robert Burns, Hamilton, Ghio, assignors to The(Iineinnati Shaper Company, machined, Ohio, a corporation of Ohio FiledJan. 6, 19631, Ser. No. 81,936 13 tilairns. (Cl. 13-465) This inventionrelates to a press for compacting powdered material such as powderedmetal into a finished product having a curved surface, and is especiallyuseful for forming curved brake linings consisting of two separate anddistinct layers of material.

Brake linings are generally used in conjunction with drum type brakes ofboth the internal-expanding and external-contracting type. In eithercase, the brake linings must be curved; for example, with aninternal-expanding brake, the curve is such that the outer radius isequal to the radius of the inside of the brake drum, and the innerradius matches that of the brake shoe. Furthermore, to promote maximumlife of the drum and shoe, the lining must be securely fastened to theshoe, and at the same time the portion which bears against the brakedrum must have a high coefiicient of friction, without causing permanentdamage to the drum. For this reason, brake linings are composed of athin and relatively hard backing layer which may be conveniently bondedto the brake shoe, and a thicker layer of material having suitablefriction characteristics.

It has been found possible to manufacture such brake linings bycompacting two layers of suitable powdered metals in conventionalpresses, but this presents several problems. In the first place, sincethe material usedin forming the backing layer is quite hard, it isimportant that the two layers of material be kept separate and distinct.Also, to promote maximum brake lining life, it is desirable that theline formed by the junction of the two layers be essentially concentricwith both the outer and inner radii of the lining itself, so that thewearing away of the friction layer takes place evenly, and no oneporrtion of the backing layer will be exposed before the rest of thatsurface.

In the conventional compacting press a feeder or other source ofpowdered material passes over a cavity, the side walls of which areformed by an appropriately shaped die and the bottom of which is formedby a curved lower punch, and dispenses its contents. As the feeder movesaway, it strikes the surface of the powder in the cavity fiat and evenwith the top of the die; the second or friction layer is then depositedin a similar fashion on top of the first or backing layer. The upperpunch, which is also curved, then presses down compacting the two layersand forming a brake lining. Linings made in this fashion suffer fromseveral disadvantages; in the first place, the line at the junction ofthe two separate layers is almost fiat rather than concentric with theinner and outer radii, and secondly the outer or friction layer has agreater density at its two ends than at its center.

Furthermore, from a mechanical standpoint, some conventional compactingpresses use a large fiat, horizontal die table which embodies twelvesets of tools. In operation, the entire die table rotates, and iscapable of production of perhaps 72 pieces per minute. The die tablerotates under the feeders, and leakage and wear are great problems.Lubrication and sealing are also difiicult, and tooling costs are quitehigh. For example, in a press which produces 72 pieces per minute withtwelve sets of tools, average production is only 6 pieces per minute perset of tools; while the total production of our machine may be somewhatlower, the rate per minute per tool is higher, and a saving in toolingcosts will result. Finally, such conventional devices seem to have aninherent tend- 3,098,261 Patented July 23, 1963 ency to get out ofadjustment, so that while only one set of tools may need an hour ofmaintenance, twelve sets of tools are idle for that entire hour, wherebytwelve hours of production time are lost.

We have now invented a novel compacting press which utilizes only asingle set of tools having a single cavity or a small number ofcavities, and is capable of producing one piece per cavity per stroke,and greatly reduces maintenance costs and lost time due to maintenance,leakage due to wear, and tooling costs.

Accordingly, it is a principal object of our invention to provide acompacting press for powdered metals which is suit-able for productionof finished products having two concentrically curved layers with aconstant density throughout the article.

It is a further object of the instant invention to provide such a presswhich reduces tooling costs, maintenance costs, and time lost due tomaintenance.

A further object of the instant invention is the provision of a novelfeeding operation for a powdered metal compacting press which depositsan evenly curved layer of the desired powdered metal.

Another object of our invention is to provide a feeding mechanism whichlargely eliminates leakage and mixing of the separate materials.

Still a further object or" our invention is to provide such a feedinoperation in which the depth of fill of the second layer is variable.

Another object of our invention is the provision of an ejection meanswhich will always return the lower punch to die table level regardlessof the variable depth of fill, and which provides overload protectionfor the entire system.

We accomplish these objects of our invention, and others which will beset out hereinafter, or which will be apparent to the worker skilled inthis art upon reading these specifications, by that certain constructionand arrangement of parts of which we shall now illustrate by means of anexemplary embodiment.

Reference is made to the accompanying drawings wherein:

FIGURES 1a to lh inclusive are a series of eight schematicrepresentations of stages in the operation of our machine;

FIGURE 2 is a side view of the machine of our invention;

FIGURE 3 is a sectional view taken along the line 3-3 of FIGURE 2;

FIGURE 4 is a sectional view taken along line 4-4 of FIGURE 3;

FIGURE 5 is a greatly enlarged sectional view of the feeder assembly ofour invention;

FIGURE 6 is a sectional view similar to the upper portion of FIGURE 4showing a modification of our invention; and

FIGURE 7 is a sectional view similar to FIGURE 6 showing still anothermodification of our invention.

Referring now to the schematic drawings of FIGURE 1, we provide a dietable 1 curved to almost the desired radius of the finished product. Inthe center of the table is a cavity indicated generally at 2 which isfonmed by coaction of the die 26 and the lower punch 3. The lower punchis securely fixed to the piston 4 of a hydraulic cylinder 5. At 6 wehave indicated a nut by means of which the total movement of thehydraulic piston is regulated. As will be described more completelylater in these specifications, the entire assembly consisting of thehydraulic cylinder 5, the piston 4-, and the lower punch 3 isreoiprocated up and down by means of a cam action shown in the otherfigures.

Above the curved die table we have indicated a brush member generally at7, a first feeder assembly generally at 8, and a second feeder assemblygenerally at 9; these members will also be described in more detailhereinafter.

When the parts are in the position shown in FIGURE 1a, the lower punchhas been moved to its uppermost position, in which it is exactly levelwith the die table, by means of the combined action of the cam and thehydraulic cylinder, and an extractor mechanism removes the finishedarticle 130. At this time, the brush 7 begins moving to the right,immediately followed by the first feeder 8; the brush cleans the dietable, the lower punch, and the upper punch as seen in FIGURE 1b. Afterthe brush has passed over the lower punch, the entire cam operatedassembly 3-5 including the lower punch makes its first drop (fixeddistance), and as shown in FIGURE 1c the first feeder 8 passes over thecavity 2a thereby formed and deposits the material for forming thebacking layer. As the first feeder 8 returns to its starting position,it strikes the powder in the cavity to the same are as the die table,and to an are which is approximately equal to the desired arc of thefinal product as will be explained later.

Then as shown in FIGURE 1d, the action of the hydraulic cylinder causesthe lower punch 3 and the piston 4 to drop to form a cavity 2b for thedeposition of the second layer of material. The distance of this seconddrop is controlled by the large nut 6 on the piston. The brush 7 thenfollows the feeder 8 and cleans the die table, as shown in FIGURE 14.The second feeder 9 then starts its arcuate motion to the left, and asshown in FIGURE 1e, deposits the material for the friction layer. As wasthe case with the first feeder, when this second feeder returns to itsstarting position, it again strikes the powder in the cavity to the sameare as the die table.

When the second feeder has returned to its original position, the entirecam operated assembly 3-5 drops to its lowermost position in which it issupported by the positive press stops 11 which bear the full pressure ofthe upper punch. This third drop permits entry of the upper punch intothe cavity without displacing the powdered layers. In FIGURES 1e, 1 andlg, we have shown a modification of our invention which will bedescribed in detail later, but basically consists of attaching the upperpunch 10 to a back-up plate 17 supported by air cylinders indicatedgenerally at 18, rather than directly attached to the eccentric operatedram. By means of this arrangement, the upper punch is accelerateddownward ahead of the ram as is clearly shown in FIGURE 1]; when thepunch contacts the powder in the cavity, it meets resistance, and so isforced upward against the slight resistance of the air cylinders.Therefore, only light pressure is maintained on the powdered layersmomentarily to allow any air entrained in the powder to escape. Fullpress tonnage is then applied when the ram '13 reaches the plate 17 asshown in FIGURE 1g. In FIGURE lit, the parts are shown returning to theoriginal position shown in FIGURE 1a; the lower punch is moved upward bythe combined action of the cam and the hydraulic cylinder, and the upperpunch is moving upward under the influence of the eccentric operatedram. When the finished article is level with the die table, an airoperated extractor (not shown) withdraws it across the :die table to adischarge chute.

Having schematically described our invention, We shall now turn to adetailed description of its embodiment. The upper punch 10 isconventionally mounted to reciprocate in guide members 12. It isattached to a ram 13 having a collar 14 surrounding an eccentric 15mounted on the main drive shaft 16. The remaining features of the driveare entirely conventional and form no part 'of our invention. The dietable 1 is mounted securely to the frame 19. A suitably shaped die(rectangular in the case of drum type brake linings) having an insert 21is mounted in the center of the table. The lower punch 3 whichreciprocates within the die insert with tolerance as close asmechanically practicable, is securely mounted to the piston 4 through aguided adapter 4a of the hydraulic cylinder 5. Port 22 is connected tothe outlet 45 from the hydraulic pump (FIGURE 2), and provides a meansof raising the piston 4. Port 23 is connected to a suitable air supply(not shown) and is used to force the piston down to allow the depositionof the friction layer of powder. The distance of this drop is controlledby the large nut 6 threaded on the piston 4; stops 24 inside thecylinder limit the upward motion of the piston. We also provide a longpin 25 extending through the base of the cylinder and into the pistonitself to prevent rotation.

The hydraulic cylinder just described is in turn supported on a member26 reciprocating within guide members 27 and fastened on its other endto cam follower 28. The cam follower is urged against the cam 29 bymeans of the bar 30 and the small cylinder 31. The profile of the cam 29is shown in FIGURE 4; it will be seen that it consists of a highsection, a first drop followed by a constant and rather long dwell, asecond drop followed by a short dwell, and then a constant rise to thehigh position. This provides the relative motion called for in theschematic description. It will be noted that in the lowest cam position,the flanged member 26 rests on the press frame members 11 which act as apositive press stop, and bear the full press tonnage. The cam 29 issecured to the cam shaft 32 which is driven by a power take-off from themain drive shaft 16. The power takeoff is conventional and comprises thematched bevel gears 33, 34, 35 and 36, and the vertical shaft 37, andserves to drive the cam shift 32 at the same speed as the main driveshaft 16. By this arrangement, we are able to maintain the exact timedrelation between the action of the upper and lower punches.

At the other end of the cam shaft 32 is mounted a second and slightlysmaller cam 38 which serves to actuate the hydraulic pump. A co-workerdisclosed, in US. Letters Patent No. 1,881,185, a hydraulic pump whichwe have found highly satisfactory. As best seen in FIGURE 2, all thecomponent parts are maintained within an oil housing 39. The pumpcomprises a cylinder 40 with a piston 4-1 normally urged upwardly by thespring 42, and having a roller 43 at its upper end which follows thecam. Oil enters the cylinder through a check valve 44, and when the camforces the piston down, oil leaves the cylinder via port 45 and goesdirectly (piping not shown) to the port 22 in the hydraulic cylinderbelow the lower punch. When the upward motion of this latter cylinder iscontained by the stops 24, excess oil flows from the cylinder 40 throughthe passage 46 into the relief cylinder 47 and urges the relief piston48 upward against the pressure of the spring 49. When the relief pistonis forced up far enough, it uncovers relief ports 50, and the oil flowsback into the reservoir. As explained earlier, the combined action ofthis hydraulic pump and the main cam 29 bring about the ejection of thefinished product. Shortly after the upper punch starts up, the ejectioncam 29 starts the upward travel of the lower punch; immediatelythereafter, the second cam 33 actuates the hydraulic pump and forces acontrolled amount of oil-to the hydraulic cylinder 5 causing a furtherupward ejection action. The combination of mechanical and hydraulicejection is a very important and novel feature of our invention. Bymeans of this combination, there is no lost motion on the ejectionstroke, regardless of the fill adjustment of the second layer ofmaterial. In other words, the whole step is accomplished in one smoothstroke with no excess travel by any component and the resulting impactas that excess is taken up. Also, the lower punch always returns exactlyto the level of the die table, again regardless of the fill adjustment.This, of course, prevents maladjustment of the extraction system,reduces wear on the lower punch, and prevents damage to a finishedarticle caused by failure of the lower punch to return to a positionlevel with the die table. system has an overload protection inherent inits design, the combination also has an overload protection.

At 51 we have shown a conventional air operated extractor which pullsthe finished article across the die table at a suitable discharge chute.

The operation of the feeder assembiles is clearly shown in FIGURE 2. Thefeeders 8 and 9 respectively are connected to arms 52 and 53 which arepivoted at the center of the die table arc. The motion of feeder 8 iscontrolled by the small cylinder 54, while a similar cylinder on theother side of the machine and hence not shown in the drawings operatesthe feeder 9. Since the feeders pivot about the center of the table are,they have no tendency to lift or shift as often occurs in conventionaloperations, and so leakage is reduced.

Similarly, the brush 7 is connected to an arm 55 and air cylinder 56,and also pivots in an arcuate path. The brush may be convenientlymounted on a hollow shaft which is connected to a light vacuum tofurther the eificiency of the cleaning operations.

In FIGURE 5 we have shown the feeder assemblies 8 and 9 (they aresubstantially identical) in more detail. They comprise a housing 57 anda rectangular spring loaded free seating bronze shoe 58 which is groundto fit the die table surface. This construction further reduces leakagecaused by wear on the table since the bronze shoe would show a similarpattern of Wear, and still be spring urged to a close fit. At the top ofthe housing, an opening 59 is provided, along withappropriateconnections to a powder supply feed 60.

In FIGURE 6 we have illustrated a modification in the construction ofthe upper punch which was briefly mentioned earlier in thesespecifications. Therein the upper punch 10 is mounted on a large guidedpunch backup plate 17, which is in turn supported by the pistons of foursmall air cylinders 18'. This pre-tamp assembly is accelerated ahead ofthe ram on its down stroke into the die cavity and places light pressureon the powder allowing air to escape prior to the main compacting.

In FIGURE 7 we have illustrated another modification of our invention.It is understoodthat in a press of this size, the finished products willhave a constant size, regardless of the small variations in the amountof powder deposited in the die cavity. Furthermore, if the size remainsconstant with varying quantities of material, density must vary.However, for many uses, it is desirable to maintain a constant density;this is especially true if certain finishing operations are to beperformed after the article comes from the press. To accomplish thisresult, we provide a special slide 61 and a guided ball seat retainer62, fastened to the ram as at 63. A diaphragm 64 of any suitablematerial is fastened to the special slide. The diaphragm chamber 65 maybe charged with any suitable material, such as, but not restric-ted to,nitrogen under pressure. The gas is completely enclosed, and will not helost unless leakage occurs or the pressure is adjusted down. With thisarrangement, the upper punch will move downward with the ram until theresistance of the powder against the upper punch equals or exceeds thepressure of the nitrogen or other material in the diaphragm chamber; atthis point, the nitrogen is more easily compressed than the powder, andso the guided ball seat retainer 62 can continue downward while the ramwith the punch remains stationary. In actual practice, we have foundthat a maximum stroke of A1 inch is sufficient for normal operation.This unit, in addition to controlling the pressure applied, acts as anoverload protection for both the press and dies.

The embodiments described are exemplary only, and numerous othermodifications will occur to those skilled in the art which do not departfrom the spirit of our invention; therefore, we intend to limitourselves in no way except as delineated in the claims which follow.

Furthermore, since the hydraulic What we claim as new and what we desireto secure by Letters Patent is:

1. A compacting press for compacting powdered material into a finishedproduct of arcuate form, comprising an eccentric driven ram, a curvedupper punch secured to said ram, a die table curved to an arcapproximately equal to the desired arc of the finished product, a diemounted in said table, a curved lower punch adapted to be reciprocatedwithin said die, means for reciprocating said lower punch, feeder meansmounted for arcuate travel over said curved die table and die, and meansfor effecting the arcuate travel of said feeder means, said feeder meansthus filling said die with said powdered material and leaving a curvedtop surface on said powdered material prior to compacting between saidcurved upper and lower punches.

2. The device claimed in claim 1, including a fluid cylinder having areciprocating piston operatively connected to said lower punch, a sourceof fluid for said cylinder, a cam driven in timed relation to saideccentric driven ram for reciprocating said fluid cylinder, whereby thecoaction of said cam and said fluid cylinder lower and raise the lowerpunch.

3. The device claimed in claim 2, including brush means mounted forarcuate travel over said die table and die in timed relation to themotion of said eccentric ram and said feeder means.

4. A press for forming brake linings from powdered material comprisingan eccentric driven ram with a curved upper punch attached thereto, adie table having a die centrally mounted therein, said die table beingcurved to an are substantially equal to the desired arc of the finishedbrake linings, a curved lower punch adapted to tbe reciprocated withinsaid die, a fluid cylinder having a reciprocating piston operativelyconnected to said lower punch, a source of fluid for said cylinder, acam driven in timed relation to said eccentric driven ram forreciprocating said piston, a first feeder secured to an arm pivoted atthe center of said die table are, means for moving said first feederarcuately from one side of said curved die table to said die and back toits starting position, a second feeder also secured to an arm pivoted atthe center of said die table arc, and means for moving said secondfeeder arcuately from the op posite side of said curved die table tosaid die and back to its starting position, said cam and said pistoncoacting to raise and lower said lower punch in timed relation to themotion of said feeders and said eccentric driven ram, and each of saidfeeder means filling said die with said powdered material and leaving acurved interface between the powdered material fed by said two feeders,and a curved top surface on said powdered material prior to compactingbetween said curved upper and lower punch members.

5. The device claimed in claim 4, wherein said cam comprises a highportion, a sudden drop followed by a relatively long dwell period, asecond sudden drop followed by a shorter dwell period, and a gradualrise back to the high portion.

6. The device claimed in claim 5, wherein said supply of fluid isoperatively connected to said cam whereby said piston, and thereforesaid lower punch, is moved downwardly between said cam drops, and ismoved upwardly during said gradual cam rise.

7. The device claimed in claim 6, wherein adjustable means are providedto limit the downward motion of said piston.

8. The device claimed in claim 7, wherein said first and second feedersare substantially identical and comprise a housing in communication witha supply of powdered metal, said housing surrounding a fully enclosingshoe member conforming to the curvature of said die table, and springmeans urging said shoe member against said die table.

9. The device claimed in claim 8, wherein said arm mounting said firstfeeder and said arm mounting said second feeder each extend beyond theirrespective pivot points, and wherein said means for moving said feedersarcuately across said die table comprise a pair of fluid cylinders eachhaving a movable piston and a supply of fluid for said cylinder, saidpistons respectively being secured to said arm extensions.

10. The device claimed in claim 9, including brush means mounted on anarm pivoted at the center of said die table are, and means for movingsaid brush means arcuately from one side of said die table to the otherand back to its starting position.

11. The device claimed in claim 10, wherein said arm mounting said brushmeans extends beyond its pivot point, and wherein said means for movingsaid brush means arcuately across said die table comprises a fluidcylinder having a movable piston, and a supply of fluid for saidcylinder, said piston being secured to said arm extension.

12. A press for forming brake linings from powdered material comprisingan eccentric driven rain with a plurality of small fluid cylinderssecured thereto, said cylinders having movable pistons, a supply offluid for said cylinders, a back-up plate secured to all of saidpistons, a curved upper punch secured to said back-up plate andextending downwardly therefrom, a die table having a die centrallymounted therein, said die table being curved to an are substantiallyequal to the desired arc of the finished brake linings, a curved lowerpunch adapted to be reciprocated within said die, a fluid cylinderhaving a reciprocating piston operatively connected to said lower punch,a source of fluid for said last named cylinder, a cam driven in timedrelation to said eccentric driven ram for reciprocating said piston, afirst feeder secured to an arm pivoted at the center of said die tableare, means for moving said first feeder areuately from one side of saidcurved die table to said die and back to its starting position, a secondfeeder also secured to an arm pivoted at the center of said die tableare, and means for moving said second feeder arcuately from the oppositeside of sai curved die table to said die and back to its startingposition, said cam and said piston coacting to raise and lower saidlower punch in timed relation to the motion of said feeders and saideccentric driven ram, and each of said feeder means filling said diewith said powdered material and leaving a curved interface between thepowdered material fed by said two feeders, and a curved top surface onsaid powdered material prior to compacting between said curved upper andlower punch members.

13. A press for forming brake linings from powdered material comprisingan eccentric driven ram, a slide having a diaphragm chamber positionedbelow said eccentric driven ram, a curved upper punch secured to saidslide and extending downwardly therefrom, a die table having a diecentrally mounted therein, said die table being curved to an aresubstantially equal to the desired arc of the finished brake linings, acurved lower punch adapted to be reciprocated within said die, a fluidcylinder having a reciprocating piston operatively connected to saidlower punch, a source of fluid for said cylinder, a cam driven in timedrelation to said eccentric driven ram for reciprocating said piston, afirst feeder secured to an arm pivoted at the center of said die tableare, means for moving said first feeder arcuately from one side of saidcurved die table to said die and back to its start ing position, asecond feeder also secured to an arm pivoted at the center of said dietable are, and means for moving said second feeder arcuately from theopposite side of said curved die table to said die and back to itsstarting position, said cam and said piston coacting to raise and lowersaid lower punch in timed relation to the motion of said feeders andsaid eccentric driven ram, and each of said feeder means filling saiddie with said powdered material and leaving a curved interface betweenthe powdered material fed by said two feeders, and a curved top surfaceon said powdered material prior to compacting between said curved upperand lower punch members.

References Cited in the file of this patent UNITED STATES PATENTS532,186 Rolf et a1. Jan. 8, 1895 532,500 Thomann Jan. 15, 1895 661,236Chisholm Nov. 6, 1900 819,005 Crichfield Apr. 24, 1906 835,737 Simmonset al. Nov. 13, 1906 994,349 Updegraif June 6, 1911 1,599,085 GibsonSept. 7, 1926 2,145,096 Schutz Jan. 24, 1939 2,275,592 Menihan Mar. 10,1942 2,350,971 Peeker et a1. June 6, 1944 2,482,342 Hubbert et a1 Sept.20, 1949 2,675,584 Frienberg et a1. Apr. 20, 1954 2,900,664 Hampel eta1. Aug. 25, 1959

1. A COMPACTING PRESS FOR COMPACTING POWDERED MATERIAL INTO A FINISHEDPRODUCT OF ARCUATE FORM, COMPRISING AN ECCENTRIC DRIVEN RAM, A CURVEDUPPER PUNCH SECURED TO SAID RAM, A DIE TABLE CURVED TO AN ARCAPPROXIMATELY EQUAL TO THE DESIRED ARC OF THE FINISHED PRODUCT, A DIEMOUNTED IN SAID TABLE, A CURVED LOWER PUNCH ADAPTED TO BE RECIPROCATEDWITHIN SAID DIE, MEANS FOR RECIPROCATING SAID LOWER PUNCH, FEEDER MEANSMOUNTED FOR ARCUATE TRAVEL OVER SAID CURVED DIE TABLE AND DIE, AND MEANSFOR EFFECTING THE ARCUATE TRAVEL OF SAID FEEDER MEANS, SAID FEEDER MEANSTHUS FILLING SAID DIE WITH SAID POWDERED MATERIAL AND LEAVING A CURVEDTOP SURFACE ON SAID POWDERED MATERIAL PRIOR TO COMPACTING BETWEEN SAIDCURVED UPPER AND LOWER PUNCHES.